I don't, but try again and see if it doesn't say so somewhere, when it rejects your photo (seems like they used to, but not always anymore).
If you want to shrink your pic, without cropping it, you can open it in paint and reduce its size by clicking on "resize" from the toolbar at the top of the page.
Make sure "percentage" is checked and you'll notice next to the categories marked "Horizontal" and "vertical" are the numbers "100".
That means the current size of the picture is 100%.
You can click on those numbers and change them.
Choosing a number less than 100 will shrink the picture down by that much (so if you changed the numbers to "70", it would be 70% of its current size).
As long as the box "maintain aspect ratio" is checked, both the horizontal and vertical dimensions will change by the same amount, simultaneously.
Don't worry about the "Skew" section down below. That's only if you want/need to distort the picture and you're not interested in that, in this case.
You only want to change the size, because a smaller picture will have less capacity (i.e., fewer "kb") and that's what the website worries about.
I find this is a far more efficient way of shrinking down the size of picture, compared to cropping.
These days, I only crop if I feel the subject of the picture doesn't appear to be the point of taking the picture.
